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TOMOYO Linux Cross Reference
Linux/include/linux/jbd2.h

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  1 /*
  2  * linux/include/linux/jbd2.h
  3  *
  4  * Written by Stephen C. Tweedie <sct@redhat.com>
  5  *
  6  * Copyright 1998-2000 Red Hat, Inc --- All Rights Reserved
  7  *
  8  * This file is part of the Linux kernel and is made available under
  9  * the terms of the GNU General Public License, version 2, or at your
 10  * option, any later version, incorporated herein by reference.
 11  *
 12  * Definitions for transaction data structures for the buffer cache
 13  * filesystem journaling support.
 14  */
 15 
 16 #ifndef _LINUX_JBD2_H
 17 #define _LINUX_JBD2_H
 18 
 19 /* Allow this file to be included directly into e2fsprogs */
 20 #ifndef __KERNEL__
 21 #include "jfs_compat.h"
 22 #define JBD2_DEBUG
 23 #else
 24 
 25 #include <linux/types.h>
 26 #include <linux/buffer_head.h>
 27 #include <linux/journal-head.h>
 28 #include <linux/stddef.h>
 29 #include <linux/mutex.h>
 30 #include <linux/timer.h>
 31 #include <linux/slab.h>
 32 #include <linux/bit_spinlock.h>
 33 #include <crypto/hash.h>
 34 #endif
 35 
 36 #define journal_oom_retry 1
 37 
 38 /*
 39  * Define JBD2_PARANIOD_IOFAIL to cause a kernel BUG() if ext4 finds
 40  * certain classes of error which can occur due to failed IOs.  Under
 41  * normal use we want ext4 to continue after such errors, because
 42  * hardware _can_ fail, but for debugging purposes when running tests on
 43  * known-good hardware we may want to trap these errors.
 44  */
 45 #undef JBD2_PARANOID_IOFAIL
 46 
 47 /*
 48  * The default maximum commit age, in seconds.
 49  */
 50 #define JBD2_DEFAULT_MAX_COMMIT_AGE 5
 51 
 52 #ifdef CONFIG_JBD2_DEBUG
 53 /*
 54  * Define JBD2_EXPENSIVE_CHECKING to enable more expensive internal
 55  * consistency checks.  By default we don't do this unless
 56  * CONFIG_JBD2_DEBUG is on.
 57  */
 58 #define JBD2_EXPENSIVE_CHECKING
 59 extern ushort jbd2_journal_enable_debug;
 60 void __jbd2_debug(int level, const char *file, const char *func,
 61                   unsigned int line, const char *fmt, ...);
 62 
 63 #define jbd_debug(n, fmt, a...) \
 64         __jbd2_debug((n), __FILE__, __func__, __LINE__, (fmt), ##a)
 65 #else
 66 #define jbd_debug(n, fmt, a...)    /**/
 67 #endif
 68 
 69 extern void *jbd2_alloc(size_t size, gfp_t flags);
 70 extern void jbd2_free(void *ptr, size_t size);
 71 
 72 #define JBD2_MIN_JOURNAL_BLOCKS 1024
 73 
 74 #ifdef __KERNEL__
 75 
 76 /**
 77  * typedef handle_t - The handle_t type represents a single atomic update being performed by some process.
 78  *
 79  * All filesystem modifications made by the process go
 80  * through this handle.  Recursive operations (such as quota operations)
 81  * are gathered into a single update.
 82  *
 83  * The buffer credits field is used to account for journaled buffers
 84  * being modified by the running process.  To ensure that there is
 85  * enough log space for all outstanding operations, we need to limit the
 86  * number of outstanding buffers possible at any time.  When the
 87  * operation completes, any buffer credits not used are credited back to
 88  * the transaction, so that at all times we know how many buffers the
 89  * outstanding updates on a transaction might possibly touch.
 90  *
 91  * This is an opaque datatype.
 92  **/
 93 typedef struct jbd2_journal_handle handle_t;    /* Atomic operation type */
 94 
 95 
 96 /**
 97  * typedef journal_t - The journal_t maintains all of the journaling state information for a single filesystem.
 98  *
 99  * journal_t is linked to from the fs superblock structure.
100  *
101  * We use the journal_t to keep track of all outstanding transaction
102  * activity on the filesystem, and to manage the state of the log
103  * writing process.
104  *
105  * This is an opaque datatype.
106  **/
107 typedef struct journal_s        journal_t;      /* Journal control structure */
108 #endif
109 
110 /*
111  * Internal structures used by the logging mechanism:
112  */
113 
114 #define JBD2_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */
115 
116 /*
117  * On-disk structures
118  */
119 
120 /*
121  * Descriptor block types:
122  */
123 
124 #define JBD2_DESCRIPTOR_BLOCK   1
125 #define JBD2_COMMIT_BLOCK       2
126 #define JBD2_SUPERBLOCK_V1      3
127 #define JBD2_SUPERBLOCK_V2      4
128 #define JBD2_REVOKE_BLOCK       5
129 
130 /*
131  * Standard header for all descriptor blocks:
132  */
133 typedef struct journal_header_s
134 {
135         __be32          h_magic;
136         __be32          h_blocktype;
137         __be32          h_sequence;
138 } journal_header_t;
139 
140 /*
141  * Checksum types.
142  */
143 #define JBD2_CRC32_CHKSUM   1
144 #define JBD2_MD5_CHKSUM     2
145 #define JBD2_SHA1_CHKSUM    3
146 #define JBD2_CRC32C_CHKSUM  4
147 
148 #define JBD2_CRC32_CHKSUM_SIZE 4
149 
150 #define JBD2_CHECKSUM_BYTES (32 / sizeof(u32))
151 /*
152  * Commit block header for storing transactional checksums:
153  *
154  * NOTE: If FEATURE_COMPAT_CHECKSUM (checksum v1) is set, the h_chksum*
155  * fields are used to store a checksum of the descriptor and data blocks.
156  *
157  * If FEATURE_INCOMPAT_CSUM_V2 (checksum v2) is set, then the h_chksum
158  * field is used to store crc32c(uuid+commit_block).  Each journal metadata
159  * block gets its own checksum, and data block checksums are stored in
160  * journal_block_tag (in the descriptor).  The other h_chksum* fields are
161  * not used.
162  *
163  * If FEATURE_INCOMPAT_CSUM_V3 is set, the descriptor block uses
164  * journal_block_tag3_t to store a full 32-bit checksum.  Everything else
165  * is the same as v2.
166  *
167  * Checksum v1, v2, and v3 are mutually exclusive features.
168  */
169 struct commit_header {
170         __be32          h_magic;
171         __be32          h_blocktype;
172         __be32          h_sequence;
173         unsigned char   h_chksum_type;
174         unsigned char   h_chksum_size;
175         unsigned char   h_padding[2];
176         __be32          h_chksum[JBD2_CHECKSUM_BYTES];
177         __be64          h_commit_sec;
178         __be32          h_commit_nsec;
179 };
180 
181 /*
182  * The block tag: used to describe a single buffer in the journal.
183  * t_blocknr_high is only used if INCOMPAT_64BIT is set, so this
184  * raw struct shouldn't be used for pointer math or sizeof() - use
185  * journal_tag_bytes(journal) instead to compute this.
186  */
187 typedef struct journal_block_tag3_s
188 {
189         __be32          t_blocknr;      /* The on-disk block number */
190         __be32          t_flags;        /* See below */
191         __be32          t_blocknr_high; /* most-significant high 32bits. */
192         __be32          t_checksum;     /* crc32c(uuid+seq+block) */
193 } journal_block_tag3_t;
194 
195 typedef struct journal_block_tag_s
196 {
197         __be32          t_blocknr;      /* The on-disk block number */
198         __be16          t_checksum;     /* truncated crc32c(uuid+seq+block) */
199         __be16          t_flags;        /* See below */
200         __be32          t_blocknr_high; /* most-significant high 32bits. */
201 } journal_block_tag_t;
202 
203 /* Tail of descriptor or revoke block, for checksumming */
204 struct jbd2_journal_block_tail {
205         __be32          t_checksum;     /* crc32c(uuid+descr_block) */
206 };
207 
208 /*
209  * The revoke descriptor: used on disk to describe a series of blocks to
210  * be revoked from the log
211  */
212 typedef struct jbd2_journal_revoke_header_s
213 {
214         journal_header_t r_header;
215         __be32           r_count;       /* Count of bytes used in the block */
216 } jbd2_journal_revoke_header_t;
217 
218 /* Definitions for the journal tag flags word: */
219 #define JBD2_FLAG_ESCAPE                1       /* on-disk block is escaped */
220 #define JBD2_FLAG_SAME_UUID     2       /* block has same uuid as previous */
221 #define JBD2_FLAG_DELETED       4       /* block deleted by this transaction */
222 #define JBD2_FLAG_LAST_TAG      8       /* last tag in this descriptor block */
223 
224 
225 /*
226  * The journal superblock.  All fields are in big-endian byte order.
227  */
228 typedef struct journal_superblock_s
229 {
230 /* 0x0000 */
231         journal_header_t s_header;
232 
233 /* 0x000C */
234         /* Static information describing the journal */
235         __be32  s_blocksize;            /* journal device blocksize */
236         __be32  s_maxlen;               /* total blocks in journal file */
237         __be32  s_first;                /* first block of log information */
238 
239 /* 0x0018 */
240         /* Dynamic information describing the current state of the log */
241         __be32  s_sequence;             /* first commit ID expected in log */
242         __be32  s_start;                /* blocknr of start of log */
243 
244 /* 0x0020 */
245         /* Error value, as set by jbd2_journal_abort(). */
246         __be32  s_errno;
247 
248 /* 0x0024 */
249         /* Remaining fields are only valid in a version-2 superblock */
250         __be32  s_feature_compat;       /* compatible feature set */
251         __be32  s_feature_incompat;     /* incompatible feature set */
252         __be32  s_feature_ro_compat;    /* readonly-compatible feature set */
253 /* 0x0030 */
254         __u8    s_uuid[16];             /* 128-bit uuid for journal */
255 
256 /* 0x0040 */
257         __be32  s_nr_users;             /* Nr of filesystems sharing log */
258 
259         __be32  s_dynsuper;             /* Blocknr of dynamic superblock copy*/
260 
261 /* 0x0048 */
262         __be32  s_max_transaction;      /* Limit of journal blocks per trans.*/
263         __be32  s_max_trans_data;       /* Limit of data blocks per trans. */
264 
265 /* 0x0050 */
266         __u8    s_checksum_type;        /* checksum type */
267         __u8    s_padding2[3];
268         __u32   s_padding[42];
269         __be32  s_checksum;             /* crc32c(superblock) */
270 
271 /* 0x0100 */
272         __u8    s_users[16*48];         /* ids of all fs'es sharing the log */
273 /* 0x0400 */
274 } journal_superblock_t;
275 
276 /* Use the jbd2_{has,set,clear}_feature_* helpers; these will be removed */
277 #define JBD2_HAS_COMPAT_FEATURE(j,mask)                                 \
278         ((j)->j_format_version >= 2 &&                                  \
279          ((j)->j_superblock->s_feature_compat & cpu_to_be32((mask))))
280 #define JBD2_HAS_RO_COMPAT_FEATURE(j,mask)                              \
281         ((j)->j_format_version >= 2 &&                                  \
282          ((j)->j_superblock->s_feature_ro_compat & cpu_to_be32((mask))))
283 #define JBD2_HAS_INCOMPAT_FEATURE(j,mask)                               \
284         ((j)->j_format_version >= 2 &&                                  \
285          ((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask))))
286 
287 #define JBD2_FEATURE_COMPAT_CHECKSUM            0x00000001
288 
289 #define JBD2_FEATURE_INCOMPAT_REVOKE            0x00000001
290 #define JBD2_FEATURE_INCOMPAT_64BIT             0x00000002
291 #define JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT      0x00000004
292 #define JBD2_FEATURE_INCOMPAT_CSUM_V2           0x00000008
293 #define JBD2_FEATURE_INCOMPAT_CSUM_V3           0x00000010
294 
295 /* See "journal feature predicate functions" below */
296 
297 /* Features known to this kernel version: */
298 #define JBD2_KNOWN_COMPAT_FEATURES      JBD2_FEATURE_COMPAT_CHECKSUM
299 #define JBD2_KNOWN_ROCOMPAT_FEATURES    0
300 #define JBD2_KNOWN_INCOMPAT_FEATURES    (JBD2_FEATURE_INCOMPAT_REVOKE | \
301                                         JBD2_FEATURE_INCOMPAT_64BIT | \
302                                         JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT | \
303                                         JBD2_FEATURE_INCOMPAT_CSUM_V2 | \
304                                         JBD2_FEATURE_INCOMPAT_CSUM_V3)
305 
306 #ifdef __KERNEL__
307 
308 #include <linux/fs.h>
309 #include <linux/sched.h>
310 
311 enum jbd_state_bits {
312         BH_JBD                  /* Has an attached ext3 journal_head */
313           = BH_PrivateStart,
314         BH_JWrite,              /* Being written to log (@@@ DEBUGGING) */
315         BH_Freed,               /* Has been freed (truncated) */
316         BH_Revoked,             /* Has been revoked from the log */
317         BH_RevokeValid,         /* Revoked flag is valid */
318         BH_JBDDirty,            /* Is dirty but journaled */
319         BH_State,               /* Pins most journal_head state */
320         BH_JournalHead,         /* Pins bh->b_private and jh->b_bh */
321         BH_Shadow,              /* IO on shadow buffer is running */
322         BH_Verified,            /* Metadata block has been verified ok */
323         BH_JBDPrivateStart,     /* First bit available for private use by FS */
324 };
325 
326 BUFFER_FNS(JBD, jbd)
327 BUFFER_FNS(JWrite, jwrite)
328 BUFFER_FNS(JBDDirty, jbddirty)
329 TAS_BUFFER_FNS(JBDDirty, jbddirty)
330 BUFFER_FNS(Revoked, revoked)
331 TAS_BUFFER_FNS(Revoked, revoked)
332 BUFFER_FNS(RevokeValid, revokevalid)
333 TAS_BUFFER_FNS(RevokeValid, revokevalid)
334 BUFFER_FNS(Freed, freed)
335 BUFFER_FNS(Shadow, shadow)
336 BUFFER_FNS(Verified, verified)
337 
338 static inline struct buffer_head *jh2bh(struct journal_head *jh)
339 {
340         return jh->b_bh;
341 }
342 
343 static inline struct journal_head *bh2jh(struct buffer_head *bh)
344 {
345         return bh->b_private;
346 }
347 
348 static inline void jbd_lock_bh_state(struct buffer_head *bh)
349 {
350         bit_spin_lock(BH_State, &bh->b_state);
351 }
352 
353 static inline int jbd_trylock_bh_state(struct buffer_head *bh)
354 {
355         return bit_spin_trylock(BH_State, &bh->b_state);
356 }
357 
358 static inline int jbd_is_locked_bh_state(struct buffer_head *bh)
359 {
360         return bit_spin_is_locked(BH_State, &bh->b_state);
361 }
362 
363 static inline void jbd_unlock_bh_state(struct buffer_head *bh)
364 {
365         bit_spin_unlock(BH_State, &bh->b_state);
366 }
367 
368 static inline void jbd_lock_bh_journal_head(struct buffer_head *bh)
369 {
370         bit_spin_lock(BH_JournalHead, &bh->b_state);
371 }
372 
373 static inline void jbd_unlock_bh_journal_head(struct buffer_head *bh)
374 {
375         bit_spin_unlock(BH_JournalHead, &bh->b_state);
376 }
377 
378 #define J_ASSERT(assert)        BUG_ON(!(assert))
379 
380 #define J_ASSERT_BH(bh, expr)   J_ASSERT(expr)
381 #define J_ASSERT_JH(jh, expr)   J_ASSERT(expr)
382 
383 #if defined(JBD2_PARANOID_IOFAIL)
384 #define J_EXPECT(expr, why...)          J_ASSERT(expr)
385 #define J_EXPECT_BH(bh, expr, why...)   J_ASSERT_BH(bh, expr)
386 #define J_EXPECT_JH(jh, expr, why...)   J_ASSERT_JH(jh, expr)
387 #else
388 #define __journal_expect(expr, why...)                                       \
389         ({                                                                   \
390                 int val = (expr);                                            \
391                 if (!val) {                                                  \
392                         printk(KERN_ERR                                      \
393                                "JBD2 unexpected failure: %s: %s;\n",         \
394                                __func__, #expr);                             \
395                         printk(KERN_ERR why "\n");                           \
396                 }                                                            \
397                 val;                                                         \
398         })
399 #define J_EXPECT(expr, why...)          __journal_expect(expr, ## why)
400 #define J_EXPECT_BH(bh, expr, why...)   __journal_expect(expr, ## why)
401 #define J_EXPECT_JH(jh, expr, why...)   __journal_expect(expr, ## why)
402 #endif
403 
404 /* Flags in jbd_inode->i_flags */
405 #define __JI_COMMIT_RUNNING 0
406 #define __JI_WRITE_DATA 1
407 #define __JI_WAIT_DATA 2
408 
409 /*
410  * Commit of the inode data in progress. We use this flag to protect us from
411  * concurrent deletion of inode. We cannot use reference to inode for this
412  * since we cannot afford doing last iput() on behalf of kjournald
413  */
414 #define JI_COMMIT_RUNNING (1 << __JI_COMMIT_RUNNING)
415 /* Write allocated dirty buffers in this inode before commit */
416 #define JI_WRITE_DATA (1 << __JI_WRITE_DATA)
417 /* Wait for outstanding data writes for this inode before commit */
418 #define JI_WAIT_DATA (1 << __JI_WAIT_DATA)
419 
420 /**
421  * struct jbd_inode - The jbd_inode type is the structure linking inodes in
422  * ordered mode present in a transaction so that we can sync them during commit.
423  */
424 struct jbd2_inode {
425         /**
426          * @i_transaction:
427          *
428          * Which transaction does this inode belong to? Either the running
429          * transaction or the committing one. [j_list_lock]
430          */
431         transaction_t *i_transaction;
432 
433         /**
434          * @i_next_transaction:
435          *
436          * Pointer to the running transaction modifying inode's data in case
437          * there is already a committing transaction touching it. [j_list_lock]
438          */
439         transaction_t *i_next_transaction;
440 
441         /**
442          * @i_list: List of inodes in the i_transaction [j_list_lock]
443          */
444         struct list_head i_list;
445 
446         /**
447          * @i_vfs_inode:
448          *
449          * VFS inode this inode belongs to [constant for lifetime of structure]
450          */
451         struct inode *i_vfs_inode;
452 
453         /**
454          * @i_flags: Flags of inode [j_list_lock]
455          */
456         unsigned long i_flags;
457 };
458 
459 struct jbd2_revoke_table_s;
460 
461 /**
462  * struct handle_s - The handle_s type is the concrete type associated with
463  *     handle_t.
464  * @h_transaction: Which compound transaction is this update a part of?
465  * @h_journal: Which journal handle belongs to - used iff h_reserved set.
466  * @h_rsv_handle: Handle reserved for finishing the logical operation.
467  * @h_buffer_credits: Number of remaining buffers we are allowed to dirty.
468  * @h_ref: Reference count on this handle.
469  * @h_err: Field for caller's use to track errors through large fs operations.
470  * @h_sync: Flag for sync-on-close.
471  * @h_jdata: Flag to force data journaling.
472  * @h_reserved: Flag for handle for reserved credits.
473  * @h_aborted: Flag indicating fatal error on handle.
474  * @h_type: For handle statistics.
475  * @h_line_no: For handle statistics.
476  * @h_start_jiffies: Handle Start time.
477  * @h_requested_credits: Holds @h_buffer_credits after handle is started.
478  * @saved_alloc_context: Saved context while transaction is open.
479  **/
480 
481 /* Docbook can't yet cope with the bit fields, but will leave the documentation
482  * in so it can be fixed later.
483  */
484 
485 struct jbd2_journal_handle
486 {
487         union {
488                 transaction_t   *h_transaction;
489                 /* Which journal handle belongs to - used iff h_reserved set */
490                 journal_t       *h_journal;
491         };
492 
493         handle_t                *h_rsv_handle;
494         int                     h_buffer_credits;
495         int                     h_ref;
496         int                     h_err;
497 
498         /* Flags [no locking] */
499         unsigned int    h_sync:         1;
500         unsigned int    h_jdata:        1;
501         unsigned int    h_reserved:     1;
502         unsigned int    h_aborted:      1;
503         unsigned int    h_type:         8;
504         unsigned int    h_line_no:      16;
505 
506         unsigned long           h_start_jiffies;
507         unsigned int            h_requested_credits;
508 
509         unsigned int            saved_alloc_context;
510 };
511 
512 
513 /*
514  * Some stats for checkpoint phase
515  */
516 struct transaction_chp_stats_s {
517         unsigned long           cs_chp_time;
518         __u32                   cs_forced_to_close;
519         __u32                   cs_written;
520         __u32                   cs_dropped;
521 };
522 
523 /* The transaction_t type is the guts of the journaling mechanism.  It
524  * tracks a compound transaction through its various states:
525  *
526  * RUNNING:     accepting new updates
527  * LOCKED:      Updates still running but we don't accept new ones
528  * RUNDOWN:     Updates are tidying up but have finished requesting
529  *              new buffers to modify (state not used for now)
530  * FLUSH:       All updates complete, but we are still writing to disk
531  * COMMIT:      All data on disk, writing commit record
532  * FINISHED:    We still have to keep the transaction for checkpointing.
533  *
534  * The transaction keeps track of all of the buffers modified by a
535  * running transaction, and all of the buffers committed but not yet
536  * flushed to home for finished transactions.
537  */
538 
539 /*
540  * Lock ranking:
541  *
542  *    j_list_lock
543  *      ->jbd_lock_bh_journal_head()    (This is "innermost")
544  *
545  *    j_state_lock
546  *    ->jbd_lock_bh_state()
547  *
548  *    jbd_lock_bh_state()
549  *    ->j_list_lock
550  *
551  *    j_state_lock
552  *    ->t_handle_lock
553  *
554  *    j_state_lock
555  *    ->j_list_lock                     (journal_unmap_buffer)
556  *
557  */
558 
559 struct transaction_s
560 {
561         /* Pointer to the journal for this transaction. [no locking] */
562         journal_t               *t_journal;
563 
564         /* Sequence number for this transaction [no locking] */
565         tid_t                   t_tid;
566 
567         /*
568          * Transaction's current state
569          * [no locking - only kjournald2 alters this]
570          * [j_list_lock] guards transition of a transaction into T_FINISHED
571          * state and subsequent call of __jbd2_journal_drop_transaction()
572          * FIXME: needs barriers
573          * KLUDGE: [use j_state_lock]
574          */
575         enum {
576                 T_RUNNING,
577                 T_LOCKED,
578                 T_FLUSH,
579                 T_COMMIT,
580                 T_COMMIT_DFLUSH,
581                 T_COMMIT_JFLUSH,
582                 T_COMMIT_CALLBACK,
583                 T_FINISHED
584         }                       t_state;
585 
586         /*
587          * Where in the log does this transaction's commit start? [no locking]
588          */
589         unsigned long           t_log_start;
590 
591         /* Number of buffers on the t_buffers list [j_list_lock] */
592         int                     t_nr_buffers;
593 
594         /*
595          * Doubly-linked circular list of all buffers reserved but not yet
596          * modified by this transaction [j_list_lock]
597          */
598         struct journal_head     *t_reserved_list;
599 
600         /*
601          * Doubly-linked circular list of all metadata buffers owned by this
602          * transaction [j_list_lock]
603          */
604         struct journal_head     *t_buffers;
605 
606         /*
607          * Doubly-linked circular list of all forget buffers (superseded
608          * buffers which we can un-checkpoint once this transaction commits)
609          * [j_list_lock]
610          */
611         struct journal_head     *t_forget;
612 
613         /*
614          * Doubly-linked circular list of all buffers still to be flushed before
615          * this transaction can be checkpointed. [j_list_lock]
616          */
617         struct journal_head     *t_checkpoint_list;
618 
619         /*
620          * Doubly-linked circular list of all buffers submitted for IO while
621          * checkpointing. [j_list_lock]
622          */
623         struct journal_head     *t_checkpoint_io_list;
624 
625         /*
626          * Doubly-linked circular list of metadata buffers being shadowed by log
627          * IO.  The IO buffers on the iobuf list and the shadow buffers on this
628          * list match each other one for one at all times. [j_list_lock]
629          */
630         struct journal_head     *t_shadow_list;
631 
632         /*
633          * List of inodes whose data we've modified in data=ordered mode.
634          * [j_list_lock]
635          */
636         struct list_head        t_inode_list;
637 
638         /*
639          * Protects info related to handles
640          */
641         spinlock_t              t_handle_lock;
642 
643         /*
644          * Longest time some handle had to wait for running transaction
645          */
646         unsigned long           t_max_wait;
647 
648         /*
649          * When transaction started
650          */
651         unsigned long           t_start;
652 
653         /*
654          * When commit was requested
655          */
656         unsigned long           t_requested;
657 
658         /*
659          * Checkpointing stats [j_checkpoint_sem]
660          */
661         struct transaction_chp_stats_s t_chp_stats;
662 
663         /*
664          * Number of outstanding updates running on this transaction
665          * [t_handle_lock]
666          */
667         atomic_t                t_updates;
668 
669         /*
670          * Number of buffers reserved for use by all handles in this transaction
671          * handle but not yet modified. [t_handle_lock]
672          */
673         atomic_t                t_outstanding_credits;
674 
675         /*
676          * Forward and backward links for the circular list of all transactions
677          * awaiting checkpoint. [j_list_lock]
678          */
679         transaction_t           *t_cpnext, *t_cpprev;
680 
681         /*
682          * When will the transaction expire (become due for commit), in jiffies?
683          * [no locking]
684          */
685         unsigned long           t_expires;
686 
687         /*
688          * When this transaction started, in nanoseconds [no locking]
689          */
690         ktime_t                 t_start_time;
691 
692         /*
693          * How many handles used this transaction? [t_handle_lock]
694          */
695         atomic_t                t_handle_count;
696 
697         /*
698          * This transaction is being forced and some process is
699          * waiting for it to finish.
700          */
701         unsigned int t_synchronous_commit:1;
702 
703         /* Disk flush needs to be sent to fs partition [no locking] */
704         int                     t_need_data_flush;
705 
706         /*
707          * For use by the filesystem to store fs-specific data
708          * structures associated with the transaction
709          */
710         struct list_head        t_private_list;
711 };
712 
713 struct transaction_run_stats_s {
714         unsigned long           rs_wait;
715         unsigned long           rs_request_delay;
716         unsigned long           rs_running;
717         unsigned long           rs_locked;
718         unsigned long           rs_flushing;
719         unsigned long           rs_logging;
720 
721         __u32                   rs_handle_count;
722         __u32                   rs_blocks;
723         __u32                   rs_blocks_logged;
724 };
725 
726 struct transaction_stats_s {
727         unsigned long           ts_tid;
728         unsigned long           ts_requested;
729         struct transaction_run_stats_s run;
730 };
731 
732 static inline unsigned long
733 jbd2_time_diff(unsigned long start, unsigned long end)
734 {
735         if (end >= start)
736                 return end - start;
737 
738         return end + (MAX_JIFFY_OFFSET - start);
739 }
740 
741 #define JBD2_NR_BATCH   64
742 
743 /**
744  * struct journal_s - The journal_s type is the concrete type associated with
745  *     journal_t.
746  */
747 struct journal_s
748 {
749         /**
750          * @j_flags: General journaling state flags [j_state_lock]
751          */
752         unsigned long           j_flags;
753 
754         /**
755          * @j_errno:
756          *
757          * Is there an outstanding uncleared error on the journal (from a prior
758          * abort)? [j_state_lock]
759          */
760         int                     j_errno;
761 
762         /**
763          * @j_sb_buffer: The first part of the superblock buffer.
764          */
765         struct buffer_head      *j_sb_buffer;
766 
767         /**
768          * @j_superblock: The second part of the superblock buffer.
769          */
770         journal_superblock_t    *j_superblock;
771 
772         /**
773          * @j_format_version: Version of the superblock format.
774          */
775         int                     j_format_version;
776 
777         /**
778          * @j_state_lock: Protect the various scalars in the journal.
779          */
780         rwlock_t                j_state_lock;
781 
782         /**
783          * @j_barrier_count:
784          *
785          * Number of processes waiting to create a barrier lock [j_state_lock]
786          */
787         int                     j_barrier_count;
788 
789         /**
790          * @j_barrier: The barrier lock itself.
791          */
792         struct mutex            j_barrier;
793 
794         /**
795          * @j_running_transaction:
796          *
797          * Transactions: The current running transaction...
798          * [j_state_lock] [caller holding open handle]
799          */
800         transaction_t           *j_running_transaction;
801 
802         /**
803          * @j_committing_transaction:
804          *
805          * the transaction we are pushing to disk
806          * [j_state_lock] [caller holding open handle]
807          */
808         transaction_t           *j_committing_transaction;
809 
810         /**
811          * @j_checkpoint_transactions:
812          *
813          * ... and a linked circular list of all transactions waiting for
814          * checkpointing. [j_list_lock]
815          */
816         transaction_t           *j_checkpoint_transactions;
817 
818         /**
819          * @j_wait_transaction_locked:
820          *
821          * Wait queue for waiting for a locked transaction to start committing,
822          * or for a barrier lock to be released.
823          */
824         wait_queue_head_t       j_wait_transaction_locked;
825 
826         /**
827          * @j_wait_done_commit: Wait queue for waiting for commit to complete.
828          */
829         wait_queue_head_t       j_wait_done_commit;
830 
831         /**
832          * @j_wait_commit: Wait queue to trigger commit.
833          */
834         wait_queue_head_t       j_wait_commit;
835 
836         /**
837          * @j_wait_updates: Wait queue to wait for updates to complete.
838          */
839         wait_queue_head_t       j_wait_updates;
840 
841         /**
842          * @j_wait_reserved:
843          *
844          * Wait queue to wait for reserved buffer credits to drop.
845          */
846         wait_queue_head_t       j_wait_reserved;
847 
848         /**
849          * @j_checkpoint_mutex:
850          *
851          * Semaphore for locking against concurrent checkpoints.
852          */
853         struct mutex            j_checkpoint_mutex;
854 
855         /**
856          * @j_chkpt_bhs:
857          *
858          * List of buffer heads used by the checkpoint routine.  This
859          * was moved from jbd2_log_do_checkpoint() to reduce stack
860          * usage.  Access to this array is controlled by the
861          * @j_checkpoint_mutex.  [j_checkpoint_mutex]
862          */
863         struct buffer_head      *j_chkpt_bhs[JBD2_NR_BATCH];
864 
865         /**
866          * @j_head:
867          *
868          * Journal head: identifies the first unused block in the journal.
869          * [j_state_lock]
870          */
871         unsigned long           j_head;
872 
873         /**
874          * @j_tail:
875          *
876          * Journal tail: identifies the oldest still-used block in the journal.
877          * [j_state_lock]
878          */
879         unsigned long           j_tail;
880 
881         /**
882          * @j_free:
883          *
884          * Journal free: how many free blocks are there in the journal?
885          * [j_state_lock]
886          */
887         unsigned long           j_free;
888 
889         /**
890          * @j_first:
891          *
892          * The block number of the first usable block in the journal
893          * [j_state_lock].
894          */
895         unsigned long           j_first;
896 
897         /**
898          * @j_last:
899          *
900          * The block number one beyond the last usable block in the journal
901          * [j_state_lock].
902          */
903         unsigned long           j_last;
904 
905         /**
906          * @j_dev: Device where we store the journal.
907          */
908         struct block_device     *j_dev;
909 
910         /**
911          * @j_blocksize: Block size for the location where we store the journal.
912          */
913         int                     j_blocksize;
914 
915         /**
916          * @j_blk_offset:
917          *
918          * Starting block offset into the device where we store the journal.
919          */
920         unsigned long long      j_blk_offset;
921 
922         /**
923          * @j_devname: Journal device name.
924          */
925         char                    j_devname[BDEVNAME_SIZE+24];
926 
927         /**
928          * @j_fs_dev:
929          *
930          * Device which holds the client fs.  For internal journal this will be
931          * equal to j_dev.
932          */
933         struct block_device     *j_fs_dev;
934 
935         /**
936          * @j_maxlen: Total maximum capacity of the journal region on disk.
937          */
938         unsigned int            j_maxlen;
939 
940         /**
941          * @j_reserved_credits:
942          *
943          * Number of buffers reserved from the running transaction.
944          */
945         atomic_t                j_reserved_credits;
946 
947         /**
948          * @j_list_lock: Protects the buffer lists and internal buffer state.
949          */
950         spinlock_t              j_list_lock;
951 
952         /**
953          * @j_inode:
954          *
955          * Optional inode where we store the journal.  If present, all
956          * journal block numbers are mapped into this inode via bmap().
957          */
958         struct inode            *j_inode;
959 
960         /**
961          * @j_tail_sequence:
962          *
963          * Sequence number of the oldest transaction in the log [j_state_lock]
964          */
965         tid_t                   j_tail_sequence;
966 
967         /**
968          * @j_transaction_sequence:
969          *
970          * Sequence number of the next transaction to grant [j_state_lock]
971          */
972         tid_t                   j_transaction_sequence;
973 
974         /**
975          * @j_commit_sequence:
976          *
977          * Sequence number of the most recently committed transaction
978          * [j_state_lock].
979          */
980         tid_t                   j_commit_sequence;
981 
982         /**
983          * @j_commit_request:
984          *
985          * Sequence number of the most recent transaction wanting commit
986          * [j_state_lock]
987          */
988         tid_t                   j_commit_request;
989 
990         /**
991          * @j_uuid:
992          *
993          * Journal uuid: identifies the object (filesystem, LVM volume etc)
994          * backed by this journal.  This will eventually be replaced by an array
995          * of uuids, allowing us to index multiple devices within a single
996          * journal and to perform atomic updates across them.
997          */
998         __u8                    j_uuid[16];
999 
1000         /**
1001          * @j_task: Pointer to the current commit thread for this journal.
1002          */
1003         struct task_struct      *j_task;
1004 
1005         /**
1006          * @j_max_transaction_buffers:
1007          *
1008          * Maximum number of metadata buffers to allow in a single compound
1009          * commit transaction.
1010          */
1011         int                     j_max_transaction_buffers;
1012 
1013         /**
1014          * @j_commit_interval:
1015          *
1016          * What is the maximum transaction lifetime before we begin a commit?
1017          */
1018         unsigned long           j_commit_interval;
1019 
1020         /**
1021          * @j_commit_timer: The timer used to wakeup the commit thread.
1022          */
1023         struct timer_list       j_commit_timer;
1024 
1025         /**
1026          * @j_revoke_lock: Protect the revoke table.
1027          */
1028         spinlock_t              j_revoke_lock;
1029 
1030         /**
1031          * @j_revoke:
1032          *
1033          * The revoke table - maintains the list of revoked blocks in the
1034          * current transaction.
1035          */
1036         struct jbd2_revoke_table_s *j_revoke;
1037 
1038         /**
1039          * @j_revoke_table: Alternate revoke tables for j_revoke.
1040          */
1041         struct jbd2_revoke_table_s *j_revoke_table[2];
1042 
1043         /**
1044          * @j_wbuf: Array of bhs for jbd2_journal_commit_transaction.
1045          */
1046         struct buffer_head      **j_wbuf;
1047 
1048         /**
1049          * @j_wbufsize:
1050          *
1051          * Size of @j_wbuf array.
1052          */
1053         int                     j_wbufsize;
1054 
1055         /**
1056          * @j_last_sync_writer:
1057          *
1058          * The pid of the last person to run a synchronous operation
1059          * through the journal.
1060          */
1061         pid_t                   j_last_sync_writer;
1062 
1063         /**
1064          * @j_average_commit_time:
1065          *
1066          * The average amount of time in nanoseconds it takes to commit a
1067          * transaction to disk. [j_state_lock]
1068          */
1069         u64                     j_average_commit_time;
1070 
1071         /**
1072          * @j_min_batch_time:
1073          *
1074          * Minimum time that we should wait for additional filesystem operations
1075          * to get batched into a synchronous handle in microseconds.
1076          */
1077         u32                     j_min_batch_time;
1078 
1079         /**
1080          * @j_max_batch_time:
1081          *
1082          * Maximum time that we should wait for additional filesystem operations
1083          * to get batched into a synchronous handle in microseconds.
1084          */
1085         u32                     j_max_batch_time;
1086 
1087         /**
1088          * @j_commit_callback:
1089          *
1090          * This function is called when a transaction is closed.
1091          */
1092         void                    (*j_commit_callback)(journal_t *,
1093                                                      transaction_t *);
1094 
1095         /*
1096          * Journal statistics
1097          */
1098 
1099         /**
1100          * @j_history_lock: Protect the transactions statistics history.
1101          */
1102         spinlock_t              j_history_lock;
1103 
1104         /**
1105          * @j_proc_entry: procfs entry for the jbd statistics directory.
1106          */
1107         struct proc_dir_entry   *j_proc_entry;
1108 
1109         /**
1110          * @j_stats: Overall statistics.
1111          */
1112         struct transaction_stats_s j_stats;
1113 
1114         /**
1115          * @j_failed_commit: Failed journal commit ID.
1116          */
1117         unsigned int            j_failed_commit;
1118 
1119         /**
1120          * @j_private:
1121          *
1122          * An opaque pointer to fs-private information.  ext3 puts its
1123          * superblock pointer here.
1124          */
1125         void *j_private;
1126 
1127         /**
1128          * @j_chksum_driver:
1129          *
1130          * Reference to checksum algorithm driver via cryptoapi.
1131          */
1132         struct crypto_shash *j_chksum_driver;
1133 
1134         /**
1135          * @j_csum_seed:
1136          *
1137          * Precomputed journal UUID checksum for seeding other checksums.
1138          */
1139         __u32 j_csum_seed;
1140 
1141 #ifdef CONFIG_DEBUG_LOCK_ALLOC
1142         /**
1143          * @j_trans_commit_map:
1144          *
1145          * Lockdep entity to track transaction commit dependencies. Handles
1146          * hold this "lock" for read, when we wait for commit, we acquire the
1147          * "lock" for writing. This matches the properties of jbd2 journalling
1148          * where the running transaction has to wait for all handles to be
1149          * dropped to commit that transaction and also acquiring a handle may
1150          * require transaction commit to finish.
1151          */
1152         struct lockdep_map      j_trans_commit_map;
1153 #endif
1154 };
1155 
1156 #define jbd2_might_wait_for_commit(j) \
1157         do { \
1158                 rwsem_acquire(&j->j_trans_commit_map, 0, 0, _THIS_IP_); \
1159                 rwsem_release(&j->j_trans_commit_map, 1, _THIS_IP_); \
1160         } while (0)
1161 
1162 /* journal feature predicate functions */
1163 #define JBD2_FEATURE_COMPAT_FUNCS(name, flagname) \
1164 static inline bool jbd2_has_feature_##name(journal_t *j) \
1165 { \
1166         return ((j)->j_format_version >= 2 && \
1167                 ((j)->j_superblock->s_feature_compat & \
1168                  cpu_to_be32(JBD2_FEATURE_COMPAT_##flagname)) != 0); \
1169 } \
1170 static inline void jbd2_set_feature_##name(journal_t *j) \
1171 { \
1172         (j)->j_superblock->s_feature_compat |= \
1173                 cpu_to_be32(JBD2_FEATURE_COMPAT_##flagname); \
1174 } \
1175 static inline void jbd2_clear_feature_##name(journal_t *j) \
1176 { \
1177         (j)->j_superblock->s_feature_compat &= \
1178                 ~cpu_to_be32(JBD2_FEATURE_COMPAT_##flagname); \
1179 }
1180 
1181 #define JBD2_FEATURE_RO_COMPAT_FUNCS(name, flagname) \
1182 static inline bool jbd2_has_feature_##name(journal_t *j) \
1183 { \
1184         return ((j)->j_format_version >= 2 && \
1185                 ((j)->j_superblock->s_feature_ro_compat & \
1186                  cpu_to_be32(JBD2_FEATURE_RO_COMPAT_##flagname)) != 0); \
1187 } \
1188 static inline void jbd2_set_feature_##name(journal_t *j) \
1189 { \
1190         (j)->j_superblock->s_feature_ro_compat |= \
1191                 cpu_to_be32(JBD2_FEATURE_RO_COMPAT_##flagname); \
1192 } \
1193 static inline void jbd2_clear_feature_##name(journal_t *j) \
1194 { \
1195         (j)->j_superblock->s_feature_ro_compat &= \
1196                 ~cpu_to_be32(JBD2_FEATURE_RO_COMPAT_##flagname); \
1197 }
1198 
1199 #define JBD2_FEATURE_INCOMPAT_FUNCS(name, flagname) \
1200 static inline bool jbd2_has_feature_##name(journal_t *j) \
1201 { \
1202         return ((j)->j_format_version >= 2 && \
1203                 ((j)->j_superblock->s_feature_incompat & \
1204                  cpu_to_be32(JBD2_FEATURE_INCOMPAT_##flagname)) != 0); \
1205 } \
1206 static inline void jbd2_set_feature_##name(journal_t *j) \
1207 { \
1208         (j)->j_superblock->s_feature_incompat |= \
1209                 cpu_to_be32(JBD2_FEATURE_INCOMPAT_##flagname); \
1210 } \
1211 static inline void jbd2_clear_feature_##name(journal_t *j) \
1212 { \
1213         (j)->j_superblock->s_feature_incompat &= \
1214                 ~cpu_to_be32(JBD2_FEATURE_INCOMPAT_##flagname); \
1215 }
1216 
1217 JBD2_FEATURE_COMPAT_FUNCS(checksum,             CHECKSUM)
1218 
1219 JBD2_FEATURE_INCOMPAT_FUNCS(revoke,             REVOKE)
1220 JBD2_FEATURE_INCOMPAT_FUNCS(64bit,              64BIT)
1221 JBD2_FEATURE_INCOMPAT_FUNCS(async_commit,       ASYNC_COMMIT)
1222 JBD2_FEATURE_INCOMPAT_FUNCS(csum2,              CSUM_V2)
1223 JBD2_FEATURE_INCOMPAT_FUNCS(csum3,              CSUM_V3)
1224 
1225 /*
1226  * Journal flag definitions
1227  */
1228 #define JBD2_UNMOUNT    0x001   /* Journal thread is being destroyed */
1229 #define JBD2_ABORT      0x002   /* Journaling has been aborted for errors. */
1230 #define JBD2_ACK_ERR    0x004   /* The errno in the sb has been acked */
1231 #define JBD2_FLUSHED    0x008   /* The journal superblock has been flushed */
1232 #define JBD2_LOADED     0x010   /* The journal superblock has been loaded */
1233 #define JBD2_BARRIER    0x020   /* Use IDE barriers */
1234 #define JBD2_ABORT_ON_SYNCDATA_ERR      0x040   /* Abort the journal on file
1235                                                  * data write error in ordered
1236                                                  * mode */
1237 #define JBD2_REC_ERR    0x080   /* The errno in the sb has been recorded */
1238 
1239 /*
1240  * Function declarations for the journaling transaction and buffer
1241  * management
1242  */
1243 
1244 /* Filing buffers */
1245 extern void jbd2_journal_unfile_buffer(journal_t *, struct journal_head *);
1246 extern void __jbd2_journal_refile_buffer(struct journal_head *);
1247 extern void jbd2_journal_refile_buffer(journal_t *, struct journal_head *);
1248 extern void __jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int);
1249 extern void __journal_free_buffer(struct journal_head *bh);
1250 extern void jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int);
1251 extern void __journal_clean_data_list(transaction_t *transaction);
1252 static inline void jbd2_file_log_bh(struct list_head *head, struct buffer_head *bh)
1253 {
1254         list_add_tail(&bh->b_assoc_buffers, head);
1255 }
1256 static inline void jbd2_unfile_log_bh(struct buffer_head *bh)
1257 {
1258         list_del_init(&bh->b_assoc_buffers);
1259 }
1260 
1261 /* Log buffer allocation */
1262 struct buffer_head *jbd2_journal_get_descriptor_buffer(transaction_t *, int);
1263 void jbd2_descriptor_block_csum_set(journal_t *, struct buffer_head *);
1264 int jbd2_journal_next_log_block(journal_t *, unsigned long long *);
1265 int jbd2_journal_get_log_tail(journal_t *journal, tid_t *tid,
1266                               unsigned long *block);
1267 int __jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block);
1268 void jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block);
1269 
1270 /* Commit management */
1271 extern void jbd2_journal_commit_transaction(journal_t *);
1272 
1273 /* Checkpoint list management */
1274 void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy);
1275 int __jbd2_journal_remove_checkpoint(struct journal_head *);
1276 void jbd2_journal_destroy_checkpoint(journal_t *journal);
1277 void __jbd2_journal_insert_checkpoint(struct journal_head *, transaction_t *);
1278 
1279 
1280 /*
1281  * Triggers
1282  */
1283 
1284 struct jbd2_buffer_trigger_type {
1285         /*
1286          * Fired a the moment data to write to the journal are known to be
1287          * stable - so either at the moment b_frozen_data is created or just
1288          * before a buffer is written to the journal.  mapped_data is a mapped
1289          * buffer that is the frozen data for commit.
1290          */
1291         void (*t_frozen)(struct jbd2_buffer_trigger_type *type,
1292                          struct buffer_head *bh, void *mapped_data,
1293                          size_t size);
1294 
1295         /*
1296          * Fired during journal abort for dirty buffers that will not be
1297          * committed.
1298          */
1299         void (*t_abort)(struct jbd2_buffer_trigger_type *type,
1300                         struct buffer_head *bh);
1301 };
1302 
1303 extern void jbd2_buffer_frozen_trigger(struct journal_head *jh,
1304                                        void *mapped_data,
1305                                        struct jbd2_buffer_trigger_type *triggers);
1306 extern void jbd2_buffer_abort_trigger(struct journal_head *jh,
1307                                       struct jbd2_buffer_trigger_type *triggers);
1308 
1309 /* Buffer IO */
1310 extern int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
1311                                               struct journal_head *jh_in,
1312                                               struct buffer_head **bh_out,
1313                                               sector_t blocknr);
1314 
1315 /* Transaction locking */
1316 extern void             __wait_on_journal (journal_t *);
1317 
1318 /* Transaction cache support */
1319 extern void jbd2_journal_destroy_transaction_cache(void);
1320 extern int  jbd2_journal_init_transaction_cache(void);
1321 extern void jbd2_journal_free_transaction(transaction_t *);
1322 
1323 /*
1324  * Journal locking.
1325  *
1326  * We need to lock the journal during transaction state changes so that nobody
1327  * ever tries to take a handle on the running transaction while we are in the
1328  * middle of moving it to the commit phase.  j_state_lock does this.
1329  *
1330  * Note that the locking is completely interrupt unsafe.  We never touch
1331  * journal structures from interrupts.
1332  */
1333 
1334 static inline handle_t *journal_current_handle(void)
1335 {
1336         return current->journal_info;
1337 }
1338 
1339 /* The journaling code user interface:
1340  *
1341  * Create and destroy handles
1342  * Register buffer modifications against the current transaction.
1343  */
1344 
1345 extern handle_t *jbd2_journal_start(journal_t *, int nblocks);
1346 extern handle_t *jbd2__journal_start(journal_t *, int blocks, int rsv_blocks,
1347                                      gfp_t gfp_mask, unsigned int type,
1348                                      unsigned int line_no);
1349 extern int       jbd2_journal_restart(handle_t *, int nblocks);
1350 extern int       jbd2__journal_restart(handle_t *, int nblocks, gfp_t gfp_mask);
1351 extern int       jbd2_journal_start_reserved(handle_t *handle,
1352                                 unsigned int type, unsigned int line_no);
1353 extern void      jbd2_journal_free_reserved(handle_t *handle);
1354 extern int       jbd2_journal_extend (handle_t *, int nblocks);
1355 extern int       jbd2_journal_get_write_access(handle_t *, struct buffer_head *);
1356 extern int       jbd2_journal_get_create_access (handle_t *, struct buffer_head *);
1357 extern int       jbd2_journal_get_undo_access(handle_t *, struct buffer_head *);
1358 void             jbd2_journal_set_triggers(struct buffer_head *,
1359                                            struct jbd2_buffer_trigger_type *type);
1360 extern int       jbd2_journal_dirty_metadata (handle_t *, struct buffer_head *);
1361 extern int       jbd2_journal_forget (handle_t *, struct buffer_head *);
1362 extern void      journal_sync_buffer (struct buffer_head *);
1363 extern int       jbd2_journal_invalidatepage(journal_t *,
1364                                 struct page *, unsigned int, unsigned int);
1365 extern int       jbd2_journal_try_to_free_buffers(journal_t *, struct page *, gfp_t);
1366 extern int       jbd2_journal_stop(handle_t *);
1367 extern int       jbd2_journal_flush (journal_t *);
1368 extern void      jbd2_journal_lock_updates (journal_t *);
1369 extern void      jbd2_journal_unlock_updates (journal_t *);
1370 
1371 extern journal_t * jbd2_journal_init_dev(struct block_device *bdev,
1372                                 struct block_device *fs_dev,
1373                                 unsigned long long start, int len, int bsize);
1374 extern journal_t * jbd2_journal_init_inode (struct inode *);
1375 extern int         jbd2_journal_update_format (journal_t *);
1376 extern int         jbd2_journal_check_used_features
1377                    (journal_t *, unsigned long, unsigned long, unsigned long);
1378 extern int         jbd2_journal_check_available_features
1379                    (journal_t *, unsigned long, unsigned long, unsigned long);
1380 extern int         jbd2_journal_set_features
1381                    (journal_t *, unsigned long, unsigned long, unsigned long);
1382 extern void        jbd2_journal_clear_features
1383                    (journal_t *, unsigned long, unsigned long, unsigned long);
1384 extern int         jbd2_journal_load       (journal_t *journal);
1385 extern int         jbd2_journal_destroy    (journal_t *);
1386 extern int         jbd2_journal_recover    (journal_t *journal);
1387 extern int         jbd2_journal_wipe       (journal_t *, int);
1388 extern int         jbd2_journal_skip_recovery   (journal_t *);
1389 extern void        jbd2_journal_update_sb_errno(journal_t *);
1390 extern int         jbd2_journal_update_sb_log_tail      (journal_t *, tid_t,
1391                                 unsigned long, int);
1392 extern void        __jbd2_journal_abort_hard    (journal_t *);
1393 extern void        jbd2_journal_abort      (journal_t *, int);
1394 extern int         jbd2_journal_errno      (journal_t *);
1395 extern void        jbd2_journal_ack_err    (journal_t *);
1396 extern int         jbd2_journal_clear_err  (journal_t *);
1397 extern int         jbd2_journal_bmap(journal_t *, unsigned long, unsigned long long *);
1398 extern int         jbd2_journal_force_commit(journal_t *);
1399 extern int         jbd2_journal_force_commit_nested(journal_t *);
1400 extern int         jbd2_journal_inode_add_write(handle_t *handle, struct jbd2_inode *inode);
1401 extern int         jbd2_journal_inode_add_wait(handle_t *handle, struct jbd2_inode *inode);
1402 extern int         jbd2_journal_begin_ordered_truncate(journal_t *journal,
1403                                 struct jbd2_inode *inode, loff_t new_size);
1404 extern void        jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode);
1405 extern void        jbd2_journal_release_jbd_inode(journal_t *journal, struct jbd2_inode *jinode);
1406 
1407 /*
1408  * journal_head management
1409  */
1410 struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh);
1411 struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh);
1412 void jbd2_journal_put_journal_head(struct journal_head *jh);
1413 
1414 /*
1415  * handle management
1416  */
1417 extern struct kmem_cache *jbd2_handle_cache;
1418 
1419 static inline handle_t *jbd2_alloc_handle(gfp_t gfp_flags)
1420 {
1421         return kmem_cache_zalloc(jbd2_handle_cache, gfp_flags);
1422 }
1423 
1424 static inline void jbd2_free_handle(handle_t *handle)
1425 {
1426         kmem_cache_free(jbd2_handle_cache, handle);
1427 }
1428 
1429 /*
1430  * jbd2_inode management (optional, for those file systems that want to use
1431  * dynamically allocated jbd2_inode structures)
1432  */
1433 extern struct kmem_cache *jbd2_inode_cache;
1434 
1435 static inline struct jbd2_inode *jbd2_alloc_inode(gfp_t gfp_flags)
1436 {
1437         return kmem_cache_alloc(jbd2_inode_cache, gfp_flags);
1438 }
1439 
1440 static inline void jbd2_free_inode(struct jbd2_inode *jinode)
1441 {
1442         kmem_cache_free(jbd2_inode_cache, jinode);
1443 }
1444 
1445 /* Primary revoke support */
1446 #define JOURNAL_REVOKE_DEFAULT_HASH 256
1447 extern int         jbd2_journal_init_revoke(journal_t *, int);
1448 extern void        jbd2_journal_destroy_revoke_caches(void);
1449 extern int         jbd2_journal_init_revoke_caches(void);
1450 
1451 extern void        jbd2_journal_destroy_revoke(journal_t *);
1452 extern int         jbd2_journal_revoke (handle_t *, unsigned long long, struct buffer_head *);
1453 extern int         jbd2_journal_cancel_revoke(handle_t *, struct journal_head *);
1454 extern void        jbd2_journal_write_revoke_records(transaction_t *transaction,
1455                                                      struct list_head *log_bufs);
1456 
1457 /* Recovery revoke support */
1458 extern int      jbd2_journal_set_revoke(journal_t *, unsigned long long, tid_t);
1459 extern int      jbd2_journal_test_revoke(journal_t *, unsigned long long, tid_t);
1460 extern void     jbd2_journal_clear_revoke(journal_t *);
1461 extern void     jbd2_journal_switch_revoke_table(journal_t *journal);
1462 extern void     jbd2_clear_buffer_revoked_flags(journal_t *journal);
1463 
1464 /*
1465  * The log thread user interface:
1466  *
1467  * Request space in the current transaction, and force transaction commit
1468  * transitions on demand.
1469  */
1470 
1471 int jbd2_log_start_commit(journal_t *journal, tid_t tid);
1472 int __jbd2_log_start_commit(journal_t *journal, tid_t tid);
1473 int jbd2_journal_start_commit(journal_t *journal, tid_t *tid);
1474 int jbd2_log_wait_commit(journal_t *journal, tid_t tid);
1475 int jbd2_transaction_committed(journal_t *journal, tid_t tid);
1476 int jbd2_complete_transaction(journal_t *journal, tid_t tid);
1477 int jbd2_log_do_checkpoint(journal_t *journal);
1478 int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid);
1479 
1480 void __jbd2_log_wait_for_space(journal_t *journal);
1481 extern void __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
1482 extern int jbd2_cleanup_journal_tail(journal_t *);
1483 
1484 /*
1485  * is_journal_abort
1486  *
1487  * Simple test wrapper function to test the JBD2_ABORT state flag.  This
1488  * bit, when set, indicates that we have had a fatal error somewhere,
1489  * either inside the journaling layer or indicated to us by the client
1490  * (eg. ext3), and that we and should not commit any further
1491  * transactions.
1492  */
1493 
1494 static inline int is_journal_aborted(journal_t *journal)
1495 {
1496         return journal->j_flags & JBD2_ABORT;
1497 }
1498 
1499 static inline int is_handle_aborted(handle_t *handle)
1500 {
1501         if (handle->h_aborted || !handle->h_transaction)
1502                 return 1;
1503         return is_journal_aborted(handle->h_transaction->t_journal);
1504 }
1505 
1506 static inline void jbd2_journal_abort_handle(handle_t *handle)
1507 {
1508         handle->h_aborted = 1;
1509 }
1510 
1511 #endif /* __KERNEL__   */
1512 
1513 /* Comparison functions for transaction IDs: perform comparisons using
1514  * modulo arithmetic so that they work over sequence number wraps. */
1515 
1516 static inline int tid_gt(tid_t x, tid_t y)
1517 {
1518         int difference = (x - y);
1519         return (difference > 0);
1520 }
1521 
1522 static inline int tid_geq(tid_t x, tid_t y)
1523 {
1524         int difference = (x - y);
1525         return (difference >= 0);
1526 }
1527 
1528 extern int jbd2_journal_blocks_per_page(struct inode *inode);
1529 extern size_t journal_tag_bytes(journal_t *journal);
1530 
1531 static inline bool jbd2_journal_has_csum_v2or3_feature(journal_t *j)
1532 {
1533         return jbd2_has_feature_csum2(j) || jbd2_has_feature_csum3(j);
1534 }
1535 
1536 static inline int jbd2_journal_has_csum_v2or3(journal_t *journal)
1537 {
1538         WARN_ON_ONCE(jbd2_journal_has_csum_v2or3_feature(journal) &&
1539                      journal->j_chksum_driver == NULL);
1540 
1541         return journal->j_chksum_driver != NULL;
1542 }
1543 
1544 /*
1545  * We reserve t_outstanding_credits >> JBD2_CONTROL_BLOCKS_SHIFT for
1546  * transaction control blocks.
1547  */
1548 #define JBD2_CONTROL_BLOCKS_SHIFT 5
1549 
1550 /*
1551  * Return the minimum number of blocks which must be free in the journal
1552  * before a new transaction may be started.  Must be called under j_state_lock.
1553  */
1554 static inline int jbd2_space_needed(journal_t *journal)
1555 {
1556         int nblocks = journal->j_max_transaction_buffers;
1557         return nblocks + (nblocks >> JBD2_CONTROL_BLOCKS_SHIFT);
1558 }
1559 
1560 /*
1561  * Return number of free blocks in the log. Must be called under j_state_lock.
1562  */
1563 static inline unsigned long jbd2_log_space_left(journal_t *journal)
1564 {
1565         /* Allow for rounding errors */
1566         unsigned long free = journal->j_free - 32;
1567 
1568         if (journal->j_committing_transaction) {
1569                 unsigned long committing = atomic_read(&journal->
1570                         j_committing_transaction->t_outstanding_credits);
1571 
1572                 /* Transaction + control blocks */
1573                 free -= committing + (committing >> JBD2_CONTROL_BLOCKS_SHIFT);
1574         }
1575         return free;
1576 }
1577 
1578 /*
1579  * Definitions which augment the buffer_head layer
1580  */
1581 
1582 /* journaling buffer types */
1583 #define BJ_None         0       /* Not journaled */
1584 #define BJ_Metadata     1       /* Normal journaled metadata */
1585 #define BJ_Forget       2       /* Buffer superseded by this transaction */
1586 #define BJ_Shadow       3       /* Buffer contents being shadowed to the log */
1587 #define BJ_Reserved     4       /* Buffer is reserved for access by journal */
1588 #define BJ_Types        5
1589 
1590 extern int jbd_blocks_per_page(struct inode *inode);
1591 
1592 /* JBD uses a CRC32 checksum */
1593 #define JBD_MAX_CHECKSUM_SIZE 4
1594 
1595 static inline u32 jbd2_chksum(journal_t *journal, u32 crc,
1596                               const void *address, unsigned int length)
1597 {
1598         struct {
1599                 struct shash_desc shash;
1600                 char ctx[JBD_MAX_CHECKSUM_SIZE];
1601         } desc;
1602         int err;
1603 
1604         BUG_ON(crypto_shash_descsize(journal->j_chksum_driver) >
1605                 JBD_MAX_CHECKSUM_SIZE);
1606 
1607         desc.shash.tfm = journal->j_chksum_driver;
1608         desc.shash.flags = 0;
1609         *(u32 *)desc.ctx = crc;
1610 
1611         err = crypto_shash_update(&desc.shash, address, length);
1612         BUG_ON(err);
1613 
1614         return *(u32 *)desc.ctx;
1615 }
1616 
1617 /* Return most recent uncommitted transaction */
1618 static inline tid_t  jbd2_get_latest_transaction(journal_t *journal)
1619 {
1620         tid_t tid;
1621 
1622         read_lock(&journal->j_state_lock);
1623         tid = journal->j_commit_request;
1624         if (journal->j_running_transaction)
1625                 tid = journal->j_running_transaction->t_tid;
1626         read_unlock(&journal->j_state_lock);
1627         return tid;
1628 }
1629 
1630 #ifdef __KERNEL__
1631 
1632 #define buffer_trace_init(bh)   do {} while (0)
1633 #define print_buffer_fields(bh) do {} while (0)
1634 #define print_buffer_trace(bh)  do {} while (0)
1635 #define BUFFER_TRACE(bh, info)  do {} while (0)
1636 #define BUFFER_TRACE2(bh, bh2, info)    do {} while (0)
1637 #define JBUFFER_TRACE(jh, info) do {} while (0)
1638 
1639 #endif  /* __KERNEL__ */
1640 
1641 #define EFSBADCRC       EBADMSG         /* Bad CRC detected */
1642 #define EFSCORRUPTED    EUCLEAN         /* Filesystem is corrupted */
1643 
1644 #endif  /* _LINUX_JBD2_H */
1645 

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